This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overarching goal of the proposed research is to determine the mechanisms of photodegradation of the natural estrogens and the effect of solvent environment on that photodegradation. Steady-state and time resolved spectroscopy and computational chemistry will be used to elucidate the photochemistry and the underlying photophysics of the estrogens. Natural estrogens are potent endocrine disruptors in surface waters, and are known to photodegrade naturally, but the mechanisms are poorly understood. Understanding how they are photodegraded in the environment may also lead to better removal strategies for the estrogens in the waste stream. The effects of solvent on the excited states of estrogens will first be determined by steady-state spectroscopy and computational chemistry. The time-dependent population of these excited states will then be determined by time-resolved spectroscopy, with guidance from computation of the excited state properties. Finally, the solvent and wavelength depedence of the photodegradation will be carried out, with product assignments being guided by infrared spectroscopy and computational modeling of likely product structures. Determining how solvent and excitation wavelength affect the population of the estrogen excited states that lead to photochemistry will allow better modeling of photodegradation in surface waters and may lead to more efficient removal strategies for the estrogens in municipal waste streams.